Finishing machine for rotary engine housing

ABSTRACT

Herein disclosed is an improved finishing machine for use in finishing an inner trochoidal surface of a rotary engine housing. The finishing machine includes regulating means for precisely regulating movement of the trochoid generating mechanism incorporated therein, and precision means coactive with the regulating means for imparting fit rotation about a stationary axis to the regulating means, whereby highly precise finishing can be obtained even where it is applied to finishing operation of a complicated inner trochoidal surface of a rotary engine housing.

United States Patent 1191 Omonishi et al.

[111 3,805,454 Apr. 23, 1974 4] FINISHING MACHINE FOR ROTARY ENGINE HOUSING [75] Inventors: Shitomi Omonishi, Hiroshima;

Masayoshi Murai; Tomonori Kimura, both of Kure, all of Japan [73] Assignee: Toyo Kogyo Co. Ltd., Aza Shinchi,

Fuchu-cho, Aki-gun, Hiroshima-ken, Japan 22 Filed: I Dec. 6,1972

[21] Appl. No.: 312,746 [30] Foreign Application Priority Data Dec. 6, 1971 v Japan ...46-989l0 [52] "aster";...i...j.;..;...;.'....,..11.;51156 R, 51/105 R [51] Int. Cl B241) 5/06 [58] Field of Search"; 51/50 R, 105, 33

[56] References Cited UNITED STATES PATENTS 2,870,578, 1/1959 Baier 51/90 3,757,474 9/l973 Pedersen 5l/33 W FOREIGN PATENTS OR APPLICATIONS l,l l7,569 6/1968 Great Britain 51/95 R Primary ExaminerAl Lawrence Smith Assistant Examiner-Nicholas P. Godici 5 7] ABSTRACT Herein disclosed is an improved finishing machine for use in finishing an inner trochoidal surface of a rotary engine housing. The finishing machine includes regu lating means for precisely regulating movement of the trochoid generating mechanism incorporated therein,

and precision means -coactive with the. regulating means for imparting fit rotation about a stationary axis to the regulating means, whereby highly precise finishw ing can be obtained even where it is applied'to finishing operation of a complicated inner trochoidal surface of a rotary engine housing.

12jClaims, 4 Drawing Figures l FINISHINGMACHINE FOR ROTARY ENGINE HOUSING BACKGROUND OF THE INVENTION the rotor and the engine housing undera hightemperature and at a high pressure differencein the working chambers. Apart from the material consideration, one of the major factors affecting the above scaling is, as pointed out by an expert of the field concerned,precise machining, especially, finishing the inner surface of the engine housing having a complicated trochoidal form. As a relevant prior art publication, reference can be made to the specification of US. Pat. No. 2,870,578, in which the basic concepts as well as their illustrative housing are disclosed.

Heretofore, however, a practical finishing machine for precisely finishing an inner trochoidal surface of a rotary engine housing has never been developed with successful results.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an improved finishing machine for precisely finishing an inner trochoidal surface of a workpiece such as a rotary engine housing.

Another object of the invention is to provide an improved finishing machine of the aforementioned type, in which regulating means is provided for precisely regulating movement of the trochoid generating mechanism.

Still another object is to provide an improved finishing machine of the afore-mentioned type, in which precision means is provided for imparting fit rotation about a stationary axis to the above regulating means.

BRIEF DESCRIPTION OF THE DRAWINGS 1 ment of the present finishing machine and explains the basic operating principles of the trochoid generating mechanism and the regulating means to be incorporated into the machine.

examples directed to machining a two-lobed engine DESCRIPTION OF THE PREFERRED EMBODIMENTS For illustrative purposes only, detailed explanation will now be made on the embodiments, in which the finishing machine according to the present invention is employed to finish or grind an inner two-lobed trochoidal surface of a workpiece such as an engine housing of a rotary engine. Referring especially to FIGS. =1 and 3, a finishing machine, as generally indicated at reference numeral 10, includes a machine housingll of a drum shape having its base 12 formed with an upright cylindrical'support13. This cylindrical support "13 has such a'considcrable height as to stably receive therein a driving shaft 14. Between the cylindrical support 13 and the driving shaft 14 is interposed, as customary, suitable bearingmeans such as roller bearings 15, 16

for rotatably support the latter in the former. The lower extension of the shaft I4 is formed with an integral bevel gear'17 which is driven by a prime mover such as a variable speed d.c. motor (not shown) by way of a bevel gear 18 meshing with the bevel gear .17. The upper extension of the shaft 14, on the other hand, is secured to an eccentric shaft 19 of a trochoid generating mechanism as generally indicated at numeral 20. The central axis 19a of the eccentric shaft 19 is, as shown, eccentricwith aneccentricity e to the axis 14a of the driving shaft 14. This eccentric shaft l9is rotatably born at its upper end 21 in. a bore 22 which is formed in the head 23of the machine housing 11 in a manner that its axis 19r-of rotation is common tothe axis 14a of the driving shaft 14. y

"The trochoid generating mechanism 20 further includes a trochoid generating casing 24 which isrotat ably born on the eccentric shaft 19 forrotatably carrin'g thereon a table shaft 25. This table shaft 25 is formed with an integral gear 26 which is in meshing engagement with a pinion 27 of the eccentric shaft 19, and extends upwardly through an opening 28 whichis formed inthe head 23 of the machine housing 11. To the upper end of the shaft 25 is secured a horizontal workpiece table 29 which removably holds or retains in position a workpiece or rotary engine housing 33 by a suitable positioning means (not shown). Thus, the inner surface 32 of the workpiece 33 can conduct a trochoidal movement relative to the common axis 14a, l9r in response to the rotation of the driving shaft 14. A supporting plate 34 may desirably be interposed between the Above the finishing machine 10 is located a slip-stone head 35 which has its axis 36 in the line common between the axis of the driving shaft 14 and the meshing point of the table shaft gear 26 with the eccentric shaft pinion 27, as will be discussed in detail with reference to FIG. 4. This slip-stone head 35 is' carried by a conventional head carrier 37 in a manner to rotate about its axis 36 and to vertically traverse. On the other hand, the head 35 is radially biased or fed toward the trochoidal surface 32 of the workpiece 33 so as to have finishing engagement therewith at an extension of the common axis l9r. As a result, the contact surface of the head 35 with the inner surface 32 precisely follow the desired trochoidal curve. If desired for more precise finishing, a template 38 may be mounted on the work piece table 29, and has an. inner surface 39 of the required trochoidal profile so as to precisely guide thereon the shaft of the head carrier 37.

According to a feature of the present invention, regulating means, as generally indicated at numeral 40, is provided in the finishing machine 10, which includes a regulating gear mechanism 41 for regulating the movement of the table shaft 25 through the trochoid generating casing 24. The gear mechanism 41 has a regulating shaft 42 which is formed with an integral pinion 43 driven directly or indirectly by the pinion 26 of the eccentric shaft 25. As will be explained in more detail with reference to FIG. 4, the axis of the regulating shaft 42 may preferably be located at an extension of a line shared between the axis 25a of the table shaft 25 and the central axis 19a of the eccentric shaft 19. The regulating shaft 42 is also rotatably born within the trochoid generating casing 24, as better seen from FIG. 1. For imparting smooth gear engagement to the regulating shaft pinion 43, an intermediate idle shaft 44 may desirably be provided in the gear mechanism 41. This idle shaft 44 is formed with an integral pinion 45 and idly rotatable within the casing 24. In consideration of radial weight balance of the casing 24 as a whole about the axis 19r, the idle shaft pinion 45 may preferably be interposed between the regulating shaft pinion 43 and the eccentric shaft pinion 27 in a manner to mesh with both of the pinions 43, 27. The regulating means 40 further includes a horizontal connecting plate 46 which is secured to the upper end of the regulating shaft 42. A standard pin 47 may preferably be rotatably born on the radially outer end, which is remote from the axis 19r of the casing 24, of the connecting plate 46. As better seen from FIG. 3, the standard pin 47 carries a supporting member 48 which in turn rotatably bears a pair of guide rollers 49a, 49b at its end portions. Between these guide rollers 49a, 49b, a pair of guide plates 5 la, 51b are provided which are mounted on the head 23 of the machine housing 11. Since the guide plates 51a, 51b have their inner surfaces horizontally inclined, on which they are engaging with each other, a suitable adjusting screw 52 may preferably be threaded into the machine housing head 23 so as to adjust the width of the two guide plates 51a, 51b. This can be made by turning the screw 52 to longitudinally move one of these plate 51a, 51b with respect to the other. On the other hand, the longitudinal direction of the plates 51a, 51b is arranged to slidably guide on their sides the guide rollers 49a, 49b, and accordingly the standard pin 47 alongan extension of a line shared between the common axis 19r and the meshing point of the table shaft gear 26 with the eccentric shaft pinion 27.

According to another important feature of the invention, precision means 60 is also provided in the finishing machine so as to provide for precisely fit rotation of thetrochoid generating casing 24 on the outer surface of the cylindrical support 13 about the common axis 19r, as shown in FIGS. 1 and 2. The precision means 60 includes an inverted cup member 61 enclosing the cylindrical support 13 and secured to the upper end of the driving shaft 14. The inner surface of the cup member 61 has its axis located at the driving shaft axis 140, while the outer surface at the central axis 19a of the eccentric shaft 19. With these in mind, the inner and outer radii are shown in FIG. 1 as respectively at r and r The cup member 61 is rotatably born fitly on the lowermost portion of the cylindrical support 13 integrally with the driving shaft 14, by a suitable means which may desirably be roller bearings 62, as easily seen from FIGS. 1 and 2. Furthermore, the precision means 60 includes a skirt member 63 which is downwardly extending from the periphery of the lower surface of the trochoid generating casing 24. This skirt member 63 has a cylindrical shape concentric with the outer surface of the cup member 61, that is, has its axis located at the central axis 19a of the eccentric shaft 19, with its radius being r The skirt member 63 is sized to enclose the cup member 61 andmovably born fitly on the lowermost portion of the member 61 integrally with the trochoid generating casing 24. For this purpose, a suitable means such as roller bearings 64 may be interposed between the cup member 61 and the skirt member 63.

Although not exemplified in the drawings, a simplified modification ofthe precision means 60 can be made which dispenses with the above-mentioned cup member 61 and skirt member 63. In this modification, the upper end of the cylindrical support 13 has an area comparative with that of the lower end of the trochoid generating casing 24. Then, the precision means 60 includes bearing means (not shown) interposed inbetween for imparting stable and smooth horizontal movement to the casing 24 relative to the machine housing 11. The bearing means may include a plurality of ball bearings (not shown) arranged over the area of the upper end of the cylindrical support 13.

Now, the operating principles of the trochoid generating mechanism 20 and the regulating means will be explained with reference to FIG. 4. As is well known in the art, when the pinion 27 and the'gear 26 having a ratio of rotation of 2 1 are intermeshing with each other, then the locus of the eccentric point 19r draws the two-lobed trochoidal curve 32 in accordance with the analytical geometry. When, therefore, the pinion 27 is rotating about the eccentric point 19r, maintaining the meshing engagement with the gear 26, on the contrary, then the workpiece 33 draws the trochoidal curve 32 at the particular axis 19r of rotation.

If, furthermore, the grinding slip-stone head 35 is located to have its axis 36 in the line N shared between the axis l9r and the meshing point M of the pinion 27 with the gear 26, the line N becomes perpendicular to the trochoidal surface 32 at the contact point 19r, thus ensuring stable griding operation. As has been described, the regulating means 40 can be said to serve the perpendicular line to coincide with the stationary line N. This is obtainable by the special arrangement that the axis 25a of the gear 26, the axis 19a of the pinion 27 and the axis 42a of the pinion 43 are located in the same line L by the trochoid generating casing 24. To the axis 42a of the regulating pinion 43, on the other hand, is secured the connecting plate 46 the other end of which is rotatably connected to the standard pin 47. The effective length of the connecting plate 46 between the axis 420 and the standard pin 47 is preset, for instance, at the value of 6 e, namely,- 6 times of the distance between the axes 19r, 19a of the pinion 27. This length relationship can be made by setting the intercept M 42a of the line L 6 times of the intercept M 1L. W ith these arrangements, therefore, the intercept 19r 19a can move in parallel relationship with the connecting plate 46, thus providing for precise griding operation at the contact point 19r independently of the angular relationship of the two characteristic lines N and L.

When the pinion 27 rotates in the direction of the arrow, more specifically, then the gear 26 and the pinion 43 (through the idle gear 45) will rotate respectively in the directions of the arrows. At this instance, let it be assumed that the pinion 27 rotates about the eccentric axis 19r by an angle of 6 from the line N, as seen clockwise. Then, the other pinion 43 also rotates in the same direction by the same angle of 8. Meanwhile, since the standard pin 47 is regulated to move back and forth along the line N, the axis 424 of the pinion 43 is swung about the standard pin 47 by the same angle 8 together with the connecting plate 46. At the same time, the trochoid generating casing 24 rotates about the meshing point M by acounter-clockwise angle of B, sothat the meshing point shifts from the original point M to the present point M. As a result, the angle M 19a M, indicates the rocking angle of the trochoid generating casing 24 about the axis 19a with respect to the rotation of the pinion 27. Since the gear 26 is formed with twice number of teeth as those of the pinion 27, the angle M 25a F turns 7(8+[3), as shown in FIG. 4. This implys that the gear .26 and the workpiece 33 rocks about the axis 25a by the angle of fi(8+fi) with respect to the casing 24.Since, in this meanwhile,the axis 25a itself rotates counter-clockwise about the meshing point M by an angle of B, the gear 26 and the workpiece 33 rotate, as seen from the stationary line N, by a r tangle of /2(8+B) B /26 1 /213. Due to these rocking and rotating movements of the gear 26 and the workpiece 33, the latter draws a trochoidal curve 32 at the eccentric shaft19r of thepinion 27. Thus,'the operating surface of the slip-stone head 35 tangentially contacts with the workpiece inner surface 32, so that precise and stable finishing of the surface '32 is obtained.

As seen at the righthand side of FIG. 4, another simplified arrangement of the regulating pinion 43 and the standardpin 47 is shown in a chain line, and is applicable to the case where the radial balance of the trochoid generating casing 24about the axis 19r is not so highly required.- In this arrangement, the intermediate idle gear 45 is dispensed and replaced'by the table shaft gear 26. The regulating pinion 43' is, in this instance, located at the side opposite to the pinion 27 and meshes with the gear 26.Fr'om the consideration as has been discussed, the axis 427a of the .pinion43' is also located in the extension of the line L, and the standard pin 47' islocatedin the extension of the line N similarly to the pin 47. The connecting plate 46' is also located symmetrically of the plate 46 with respect to the meshing point M. i i

The finishing machine according to the present in- 'vention should be appreciated in the following points:

With use of the precision means60, the trochoid generating mechanism is assembled in compact, with the resultant finishing or grinding operation improved to be condirably stable and precise.

With use of the regulating means 40, moreover, the locating operation of the guide line of the guide rollers 49a, 49b is considerably simplified, because the guide plate 51a, 51b are easily positioned with reference vto the adjoining gear members such as the pinions 43, 27 and the gears 45; 26 which have their respective axes 42a, 19a, 44a and a located at the common line N. This merit is reflected by an accompanying advantage that proper maintenance and inspection can be made relatively easily on the finishing machine of the invention.

What is claimed is:

l. A finishing machine for finishing an inner trochoi dal surface of a workpiece, comprising:

a machine housing having its base formed with an upright cylindrical support of considerable height and its head formed with a bore and an opening;

a driving shaft rotatably born in the cylindrical support of said machine housing and extending into said machine housing;

an eccentric shaft having its central axis eccentric to the axisof said driving shaft arid formed with an integral pinion, said. eccentric shaft having its upper end rotatably born in the bore of said head and its lower end secured to the extending end of said driving shaft such that the axis of rotation thereof is common to that of said driving shaft;

a table shaft formed with an integral gear meshing with the pinion of said eccentric shaft and up wardly extending through the opening of said machine housing;

a horizontal workpiece table secured to the upper end of said table shaft and removably holdingthe workpiece in position for carrying the same;

a trochoid generating casing disposed within said machine housing and rotatably born on said eccentric shaftfor rotatably carrying thereon said table shaft in a predetermined pattern of movement relative to the axis of rotation of said eccentric shaft;

precision means for providing forprecisely fit rotation of said trochoid generating casing on the outer sidesurface of the cylindrical support of said machine housingrelative to the axis of rotation of said eccentric shaft;

regulatinggear mechanism including a regulating shaft formed with an integral pinion driven by the pinion of said eccentric shaft, said regulating shaft being rotatably born within said trochoid generating casing; horizontal connecting plate secured to the upper end of said regulating shaft; standard pin rotatably born on the radially outer end of said connecting plate; pair of guide rollers carriedby said standard pin; pair of guide plates mounted on the head of said machine housing and interposed between said guide rollers, said guideplates being arranged to slidably guide thereon said guide rollers and accordingly said standard pin along anextension of a line shared between the axis of saiddriving shaft andthe meshing point of the gear of said table shaft with the pinion of said eccentric shaft; and grinding head having its axis located in the line shared between the axis of said driving shaft and said meshingpoint, said grinding head being biased to have finishing engagement with the inner trochoidal surface of the'workpiece at an extension of the axis of said driving shaft. 2. A finishing machine according to claim 1, further 2 comprising a supporting plate mounted on the upper surface of said machine housing for slidably supporting thereon said workpiece table.

3. A finishing machine according to claim 1, wherein 4. A finishing machine according to claim 1, wherein the upper end of the cylindrical support of said ma chine housing has an area comparative with that of the lower end of said trochoid generating casing, and wherein said precision means includes bearing means interposed between the upper end of said cylindrical support and the lower end of said casing for imparting stable horizontal movement to said casing relative to said machine housing.

5. A finishing machine according to claim 4, wherein said bearing means includes a plurality of ball bearings arranged over the area of the upper end of said cylindrical support.

6. A finishing machine according to claim 1, wherein said precision means includes an inverted cup member enclosing said cylindrical support and secured to the upper end of said driving shaft, said cup member including a cylindrical side portion the inner surface of which has its axis located at the axis of said driving shaft and the outer surface of which has its axis located at the central axis of said eccentric shaft, said cup member being rotatably born fitly on the lowermost portion of said cylindrical support integrally with said driving shaft, and a skirt member downwardly extending from the periphery of the lower surface of said trochoid generating casing and having a cylindrical shape with its axis located at the central axis of said eccentric shaft, said skirt member being sized to enclose said cup member and movably born fitly on the lowermost portion of said cup member integrally with said casing.

7. A finishing machine according to claim 1, wherein the pinion of said regulating shaft is directly driven by the pinion of said eccentric shaft.

8. A finishing machine according to claim 1, wherein the pinion of said regulating shaft is indirectly driven by the pinion of said eccentric shaft.

9. A finishing machine according to claim 8, wherein the pinion of said regulating shaft meshes with the gear of said table shaft.

10. A finishing machine according to claim 8, wherein said gear mechanism further includes an intermediate idle shaft formed with an integral intermediate gear meshing with both of the pinions of said eccentric shaft and regulating shaft.

11. A finishing machine according to claim 8, wherein said idle shaft has its axis located at the extension of the line shared between the axis of said table shaft and the central axis of said eccentric shaft.

12. A finishing machine according to claim 1, further comprising a template mounted on said workpiece table and having an inner surface similar to the desired trochoidal profile for precisely guiding thereon said grinding head. 

1. A finishing machine for finishing an inner trochoidal surface of a workpiece, comprising: a machine housing having its base formed with an upright cylindrical support of considerable height and its head formed with a bore and an opening; a driving shaft rotatably born in the cylindrical support of said machine housing and extending into said machine housing; an eccentric shaft having its central axis eccentric to the axis of said driving shaft and formed with an integral pinion, said eccentric shaft having its upper end rotatably born in the bore of said head and its lower end secured to the extending end of said driving shaft such that the axis of rotation thereof is common to that of said driving shaft; a table shaft formed with an integral gear meshing with the pinion of said eccentric shaft and upwardly extending through the opening of said machine housing; a horizontal workpiece table secured to the upper end of said table shaft and removably holding the workpiece in position for carrying the same; a trochoid generating casing disposed within said machine housing and rotatably born on said eccentric shaft for rotatably carrying thereon said table shaft in a predetermined pattern of movement relative to the axis of rotation of said eccentric shaft; precision means for providing for precisely fit rotation of said trochoid generating casing on the outer side surface of the cylindrical support of said machine housing relative to the axis of rotation of said eccentric shaft; a regulating gear mechanism including a regulating shaft formed with an integral pinion driven by the pinion of said eccentric shaft, said regulating shaft being rotatably born within said trochoid generating casing; a horizontal connecting plate secured to the upper end of said regulating shaft; a standard pin rotatably born on the radially outer end of said connecting plate; a pair of guide rollers carried by said standard pin; a pair of guide plates mounted on the head of said machine housing and interposed between said guide rollers, said guide plates being arranged to slidably guide thereon said guide rollers and accordingly said standard pin along an extension of a line shared between the axis of said driving shaft and the meshing point of the gear of said table shaft with the pinion of said eccentric shaft; and a grinding head having its axis located in the line shared between the axis of said driving shaft and said meshing point, said grinding head being biased to have finishing engagement with the inner trochoidal surface of the workpiece at an extension of the axis of said driving shaft.
 2. A finishing machine according to claim 1, further comprising a supporting plate mounted on the upper surface of said machine housing for slidably supporting thereon said workpiece table.
 3. A finishing machine according to claim 1, wherein said regulating shaft has its axis located at an extension of a line shared between the axis of said table shaft and the central axis of said eccentric shaft.
 4. A finishing machine according to claim 1, wherein the upper end of the cylindrical support of said machine housing has an area comparative with that of the lower end of said trochoid generating casing, and wherein said precision means includes bearing means interposed between the upper end of said cylindrical support and the lower end of said casing for imparting stable horizontal movement to said casing relative to said machine housing.
 5. A finishing machine according to claim 4, wherein said bearing means includes a plurality of ball bearings arranged over the area of the upper end of said cylindrical support.
 6. A finishing machine according to claim 1, wherein said precision means includes an inverted cup member enclosing said cylindrical support and secured to the upper end of said driving shaft, said cup member including a cylindrical side portion the inner surface of which has its axis located at the axis of said driving shaft and the outer surface of which has its axis located at the central axis of said eccentric shaft, said cup member being rotatably born fitly on the lowermost portion of said cylindrical support integrally with said driving shaft, and a skirt member downwardly extending from the periphery of the lower surface of said trochoid generating casing and having a cylindrical shape with its axis located at the central axis of said eccentric shaft, said skirt member being sized to enclose said cup member and movably born fitly on the lowermost portion of said cup member integrally with said casing.
 7. A finishing machine according to claim 1, wherein the pinion of said regulating shaft is directly driven by the pinion of said eccentric shaft.
 8. A finishing machine according to claim 1, wherein the pinion of said regulating shaft is indirectly driven by the pinion of said eccentric shaft.
 9. A finishing machine according to claim 8, wherein the pinion of said regulating shaft meshes with the gear of said table shaft.
 10. A finishing machine according to claim 8, wherein said gear mechanism further includes an intermediate idle shaft formed with an integral intermediate gear meshing with both of the pinions of said eccentric shaft and regulating shaft.
 11. A finishing machine accoRding to claim 8, wherein said idle shaft has its axis located at the extension of the line shared between the axis of said table shaft and the central axis of said eccentric shaft.
 12. A finishing machine according to claim 1, further comprising a template mounted on said workpiece table and having an inner surface similar to the desired trochoidal profile for precisely guiding thereon said grinding head. 